Flexible permanent magnet



Nov. 26, 1963 R. ELLIS 3,111,735

FLEXI'BLE PERMANENT MAGNET Filed April 10, 1961 IN V EN TOR.

United States Patent 3,111,735 FLEXIBLE PENENT MAGNET Robert Eiiis, San Diego, Caiif. (350 E. Plaza, Solana Beach, tlalif.) Filed Apr. 10, 161,Ser. No. 113,576 8 Claims. (ill. 24-20l) This invention relates to a flexible permanent magnet and process of making same and the principal object of the invention is the provision of means for increasing the magnetic attraction of a permanent magnet over the construction shown in my previous Patent No. 2,627,097 issued February 3, 195 3.

Another object of the invention is the provision of means for providing an extremely flexible permanent magnet and its associated armature each from a single piece of suitable material.

And still another object of the invention is the provision of means for applying the flexible permanet magnet and armature to various types of flexible closures.

Other and further objects will appear in the specifications and be specifically pointed out in the appended claims, reference being had to the accompanying drawings exemplifying the invention, and in which:

FIG. 1 shows the development of the magnet before bending it into the preferential U-shape and filling the slots with soft rubber.

FIG. 2 is a composite cross section of both magnet and armature after forming and completion taken on the line 22 of FIG. 1 and on line 2A2A of FIG. 3.

FIG. 3 shows the development of the armature before filling the slots with soft rubber.

FIG. 4 illustrates the application of the magnet in a butt closure.

FIG. 5 is a cross section on the line 5-5 of FIG. 4.

HG. 6 illustrates by cross section a slight variation of the magnet.

FIG. 7 illustrates the process of applying an elastic material, such as soft rubber, within the slots of the magnet and armature.

Referring to the drawings in which like characters and numerals of reference refer to similar parts throughout the several views, the numeral 8 denotes a thin strip of magnetizable material such as sheet steel in which numerous equally spaced slots 9 are punched therein from each oppositely disposed longitudinal side thereof, these slots definitely extending from the open end of each slot past the center of the strip and preferably past both dotted lines it) at which intersections the longitudinal sides of the strip 8 are preferably bent over inward into a U-shape as better illustrated in FIG. 2. The parts 11 between the slots 9 thus form the poles of permanent magnets when magnetized in the usual manner, all the magnets on one longitudinal side being preferably north pole and on the opposite longitudinal side south pole, denoted by N and S respectively. It will be noted that the slots 9 are so narrow that magnetic leakage on a prohibitive scale would occur of the alternate magnetic poles on one longitudinal edge of strip 8 were of opposite polarity, so the poles are all either a N or S pole on each respective edge. Slits 12 may also be used as illustrated to permit still better flexibility of the strip, these slits in no way detracting from the strength of the magnetic force as, regardless of the transverse cut in the strips on each side of the slit 12, the metal is still touching and no magnetic loss results as will be readily understood. It will thus be apparent that the strip 8 may now be easily flexed in any direction and still retain the magnetic attraction of a solid permanent magnet but adapted to be used with flexible closures. It has been found that magnetizable powder mixed with 371 1 1 Patented Nov. 26, 1963 "ice a binder such as rubber and permanently magnetized has the magnetizable qualities reduced to only five percent of that of solid steel, incidentally reducing the flexibility of the rubber to a great extent, hence, by making the rigid solid metal flexible in such form as also to be able to provide suitable permanent magnet poles thereto, is the essence of this invention.

The armature strip 13 may also be made of similar material and may or may not be permanently magnetized as desired, in this case, see FIG. 3, the slots 9 are punched from both longitudinal sides of the strip 13 and in line with each other but prevented from meeting by means of the narrow connecting parts 14 which are staggered so as to permit the strip greater flexibility in all directions as will be readily understood. The armature strip 13 preferably remains flat as illustrated in FIG. 3 and is only wide enough to straddle the pole pieces N and S of the permanent magnet 8, see FIG. 2. The slots 9 of the armature 13 are sufficiently narrow to permit some part of the magnet poles N and S to be in physical contact at all times in any position. In case it is desired to increase the magnetic traction between the magnet 8 and armature 13, the ends 11A of the armature 13 may also be magnetized but of opposite polarity to that of the magnet 8 as better illustrated in FIGS. 1 and 3.

The flexible permanent magnet 8 and its associated flexible armature 13 may now be used in many dilferent applications such as with flexible closures in shoes, wearing apparel, etc., in which case the armature 13 should preferably be provided with an upstanding longitudinal flexible non-magnetic guide-strip 15, composed of material such as soft rubber, adapted to fit snugly into the space between the legs of the U-shaped perma nent magnet 8 as better illustrated in FIG. 2, the flexible soft rubber material 20 also permeating into the slots 9, also in magnet 8. The insertion of the soft rubber guide strip 15 into the magnet space as above described will prevent physical disconnection of the magnet and armature when the two opposite flaps 16 and 17 of the flexible closure exert strain in the direction of arrows l8 and 119 respectively as well as secure them at right angles through magnetic attraction.

For a butt closure as for shoes illustrated in FIG. 4, I

the numeral 21 denotes generally an overshoe having the customary foot opening 22 and side flaps 23 and 24 respectively to the margins of which the flexible magnetic closure elements 8 and 13 are attached as illustrated in FIG. 4, the element 8 comprising the permanent magnet and 1.3 the armature, the longitudinal edges of which are designed to contact the pole pieces N and S of the magnet 8 along its entire length when in closed position. FIG. 5 shows in section how the armature and magnet are always in closed position at the toe end of the shoe so that all that is necessary in order to close the flaps 23 and 24 is to lightly press a finger over thereon, the magnetic attraction between the two elements automatically closing them without the customary use of any tab.

It will of course be understood that the thickness and composition of the magnetic elements 8 and 13 are such as to satisfactorily quality for the desired resiliency and flexibility for each particular use and in case extra flexibility and magnetic traction is required, a plurality of similar strips 8 and 8A may be superimposed as illustrated by the sectional view FIG. 6.

The soft rubber or plastic insert material 20 may easily fill the slots 9 of both the magnet 8 and armature 13 by passing the reel of strip material 813 in the direction of arrow 25 through the automatic punch 30 and extending press 26 and die 27, the soft rubber material being fed through the hopper 28. The finished product is wound onto reel 29. Suitable length strips are then cut off the reeled strip for each particular use. The armature 13 is of course produced in the same manner.

From the foregoing descriptioin it will be apparent that I have evolved a flexible permanent magnet having particular use for attachment to the closure flaps of wear ing apparel, shoes, etc., which magnetic elements can be manufactured cheaply, will permit the retention of a maximum of magnetic tractive force, is neat and attractive in appearance, will render the closure waterproof when in closed position and can be easily manipulated into open or closed position merely with the use of two fingers.

Various changes may be made in the embodiment of the invention hereinabove specifically described Without departing from or sacrificing the advantages of the invention as defined in the appended claims.

I claim:

1. A flexible permanent magnetic closure comprising two relatively thin strips of magnetizable sheet metal, each of said strips having equally spaced transverse slots cut therein alternately from each opposite longitudinal side thereof, one of said strips being bent substantially U- shape in cross section and permanently magnetized with like magnetic poles on each respective longitudinal edge thereof while the other strip is the armature and adapted to contact the poles of said permanent magnet when said strips are attached longitudinally each along a margin of opposite flaps of a flexible closure article.

2. As in claim 1, the end of each of said alternating transverse slots extending past each other.

3. As in claim 1, the said associated armature strip being flat and having attached to its longitudinal center a longitudinal non-magnetic flexible guide strip adapted to snugly fit into the longitudinal lJ-shaped depression of the permanently magnetized strip.

4. As in claim 1, and means for superimposing another similar but slightly larger U-shaped permanently magnetized strip over the other U-shaped permanently magnetized strip.

5. As in claim 1, the upstanding longitudinal rear face of said permanent magnet and the rear face of said arma- 4i ture being adapted to be covered and the slots permeated by a flexible binding material such as rubber.

6. A flexible permanent magnet comprising originally a flat strip of bendable magnetizable steel, narrow closely spaced transverse slots in said strip, each of said slots extending transversely and alternately from one longitudinal side of said strip and terminating close to the opposite side thereof, said steel strip being bent longitudinally into a horse-shoe shape and permanently magnetized with a north magnetic pole on one longitudinal edge and a south magnetic pole on the opposite longitudinal edge thereof.

7. As in claim 6, and an associated armature, said armature comprising a flat strip of bendable magnetically attractive steel, narrow closely spaced transverse slots in said strip, each of said slots extending transversely and alternately from one longitudinal side of said strip and terminating close to the opposite side thereof, and a longitudinal non-magnetic flexible guide strip adapted to loosely fit into the longitudinal horse-shoe shaped depression of the permanently magnetized strip attached to the longitudinal center of said armature.

8. A flexible permanent magnetic closure comprising two relatively thin strips of magnetizable sheet metal, each of said strips having equally spaced transverse slots cut therein alternately from each opposite longitudinal side thereof, one of said strips being bent substantially U-shape in cross-section and permanently magnetized while the other strip is adapted to contact the longitudinal poles of said permanent magnet when said strips are attached longitudinally along the margins of opposite flaps of a flexible closure article.

References Cited in the file of this patent UNITED STATES PATENTS 1,775,981 Warner Sept. 16, 1930 2,252,305 Puschner Aug. 12, 1941 2,389,298 Ellis Nov. 20, 1945 2,397,331 Winter-halter Mar. 26, 1946 2,397,931 Ellis Apr. 9, 1946 2,432,819 Schurnacker Dec. 16, 1947 2,627,097 Ellis Feb. 3, 1953 

1. A FLEXIBLE PERMANENT MAGNETIC CLOSURE COMPRISING TWO RELATIVELY THIN STRIPS OF MAGNETIZABLE SHEET METAL, EACH OF SAID STRIPS HAVING EQUALLY SPACED TRANSVERSE SLOTS CUT THEREIN ALTERNATELY FROM EACH OPPOSITE LONGITUDINAL SIDE THEREOF, ONE OF SAID STRIPS BEING BENT SUBSTANTIALLY USHAPE IN CROSS SECTION AND PERMANENTLY MAGNETIZED WITH LIKE MAGNETIC POLES ON EACH RESPECTIVE LONGITUDINAL EDGE THEREOF WHILE THE OTHER STRIP IS THE ARMATURE AND ADAPTED TO CONTACT THE POLES OF SAID PERMANENT MAGNET WHEN SAID STRIPS ARE ATTACHED LONGITUDINALLY EACH ALONG A MARGIN OF OPPOSITE FLAPS OF A FLEXIBLE CLOSURE ARTICLE. 